Following last year's headline-making turn in "Spring Breakers," followed by roles in "Machete Kills" and "The Frozen Ground," Vanessa Hudgens continues to shatter her squeaky clean image with her latest indie drama, "Gimme Shelter."

With short, dark locks and a few pounds added to her petite frame, Hudgens is far from glam in her role as a troubled teen who discovers she is pregnant. Rosario Dawson stars as Hudgens' crack-addicted mother — also unrecognizable in her role — while Brendan Frasier plays the white-collar dad Hudgens never knew.

"Looking at myself in the mirror and not being able to recognize myself was a very special and exciting and thrilling thing to be able to experience," the "High School Musical" alum told MTV News. "It really reminded me that I couldn't go too far with my physicality or my dialect, just because I already was not me."

Based on a true story, "Gimme Shelter" follows a young teen named Apple as she finds a home in the real-life pregnancy shelter run by Kathy DiFiore. To prep for the role, Hudgens actually moved into the shelter to live side-by-side with its inhabitants. But even before landing the role, she had already proved herself to be one of the girls.

"She turned in a great audition and I was convinced, but I really needed the trust from the girls," writer-director Ron Krauss told MTV News. He sent over footage of several auditions for DiFiore and the young mothers to watch before casting the role, but it was Hudgens who blew them away.

"They said, 'That girl! That girl needs to be the person who plays the role. That's us,'" he recalled. "When they picked her, that was the confirmation. I just knew it."

Dawson called the overall experience "intense," and we can't blame her. The 34-year-old gets extremely physical in the role, engaging in multiple knock down, drag out fights with her on-screen daughter.

"I had bruises all over," Dawson said. "You just don't think about it 'cause you're filming. I remember I kept looking later like, 'Why do I have all these bruises all over me?' ... You just get caught up in the emotion of it."